Are there any rewards for Splatoon 2’s rhythm game

I've finished the campaign, so I feel comfortable saying that the eggs are all fairly balanced at roughly ~200+ per normal level. It seems that if you just go through and do each weapon challenge on a level it will fill up your eggs quite well after completely clearing all challenges on a normal level or two. You're probably also going to have to replay levels anyways to find the sardinium you need to upgrade them anyways.

By beating every mission in Splatoon 2's Octo Canyon you unlock the hero replica of the weapon you beat all the missions with. The only exception to this is the Hero Brella which isn't released yet and Sheldon tells you that he is currently working on it, meaning this weapon should be released at a future date.